1. Field of the Invention
The invention relates to a method for creating a three-dimensional effect, in which method the three-dimensional effect is created by viewing an object, for instance two disparate images, by means of an optical aid. The invention relates further to an arrangement for creating a three-dimensional effect.
2. Description of the Prior Art
Three-dimensional effect can be utilized when viewing for instance photographs, diapositives, textbooks, nature books, installation manuals, computer displays, product brochures, advertisements, etc.
Previously known stereoscopic viewing devices are similar to a binocle or spectacles, i.e. devices intended for a viewer's both eyes. The devices may be unsuitable for the viewer's sight, and therefore, they are often provided with adjusting means to adapt them to the viewer's sight. However, adjusting means are often very unhandy and suitable for use within certain limits only. Blinders of many kinds have also often been used in previously known devices for limiting the viewing area. The blinders are to be adjusted according to the distance between the eyes as well as according to image size and viewing distance. When the image size changes, a readjustment is necessary, which makes the viewing uncomfortable. In addition, the known devices are intended for viewing images in the horizontal plane; it is difficult to adjust them for viewing images deviating from the horizontal plane. The previous viewing devices are inconvenient in use and their manufacturing costs are high, and therefore, they have been used very little. Viewing by means of the previous devices can be called "tube viewing", which is a very limited way of viewing, meaning that only a limited area is seen.
As examples of said previously known technique may be set forth in this connection the solutions disclosed in U.S. Pat. Nos. 4,429,951, 4,717,239, 4,730,898 and 4,986,632. Drawbacks of these solutions are the very facts mentioned above, which have prevented them from coming into common use.
As additional examples of known solutions in the field may be mentioned the solutions disclosed in U.S. Pat. No. 5,119,234, European Patent Application 0 204 867 and German Offenlegungsschrift 3 305 444. However, all these solutions function on the same principle as spectacles, which means that optical aids are arranged fixedly before the viewer's eyes, because of which the viewer has to move closer to and farther off the image and the sharpness disappears. A further problem is that these devices are more difficult to use if the viewer wears spectacles.